Field of the Invention
The present invention relates to a fixing apparatus and an image forming apparatus.
Description of Related Art
Conventionally, an image forming apparatus employing the electro-photographic method includes a fixing apparatus which fixes color material (toner) transferred from an image carrier (photoreceptor drum, intermediate transfer belt, etc.) to a sheet by applying heat and pressure. A well-known fixing apparatus is provided with reflecting plates and heat insulating plates around the heating unit in order to enhance heating efficiency in the fixing apparatus.
For example, Japanese Patent Application Laid-Open Publication No. 2004-109626 proposes a fixing apparatus provided with a concave/convex portion in a portion of the reflecting plate provided surrounding the heating unit to face the heating unit in order to prevent natural convection between the heating unit and the reflecting plate. In such fixing apparatus, it is possible to suppress the flow of air in the circling direction of the heating unit and to prevent the hot air heated by the heating unit from going outside.
However, when the reflecting plate provided with a concave/convex portion as described in the conventional technique is employed, the concave/convex portion prevents the flow of air between the reflecting plate and the heating unit. Therefore, the warm air filled around the heating unit when the temperature of the heating unit rises too high is not discharged and a certain amount of time is necessary to return the temperature to a suitable temperature.
As described above, there are points for modification in the fixing apparatus provided with a concave/convex portion in the portion of the reflecting plate facing the heating unit from the viewpoint of controlling the temperature of the heating unit.